Integrated Event Detection and Electrical Generator Devices For A Gravity Dropped or Ejected Weapons

ABSTRACT

A method for generating power in a gravity dropped munition, the method including: winding a cable around a drum of a generator associated with the munition; attaching the cable from the generator to a portion of an aircraft; separating the munition from the aircraft to unwind the cable from the drum to release the cable from the drum after a predetermined amount of rotation of the drum; converting the rotation of the drum to energy in a spring as the cable is unwound from the drum; restricting movement of an intermediate member connecting the drum to the generator while the cable is being unwound from the drum; and ending the restricting when the cable is released from the drum allowing the intermediate member to engage the drum with the generator to produce power from the generator.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit to earlier filed U.S. ProvisionalPatent Application Nos. 62/510,222, filed May 23, 2017 and 62/581,679,filed on Nov. 4, 2017, the entire contents of each of which areincorporated herein by reference.

GOVERNMENT RIGHTS

This invention was made with Government support under contractFA8651-10-C-0145 awarded by the United States Air Force. The Governmenthas certain rights in the invention.

BACKGROUND 1. Field

The present disclosure is generally directed to safe arm fuses and powergeneration devices for gravity dropped or ejected weapons, and moreparticularly to gravity dropped or ejected weapon release eventdetection and power generation onboard gravity dropped or ejectedweapons.

2. Prior Art

All weapon systems require fuzing systems for their safe and effectiveoperation. A fuze or fuzing system is designed to provide as a primaryrole safety and arming functions to preclude munitions arming before thedesired position or time, and to sense a target or respond to one ormore prescribed conditions, such as elapsed time, pressure, or command,and initiate a train of fire or detonation in a munition.

Fuze safety systems consist of an aggregate of devices (e.g.,environment sensors, timing components, command functioned devices,logic functions, plus the initiation or explosive train interrupter, ifapplicable) included in the fuze to prevent arming or functioning of thefuze until a valid environment has been sensed and the arming delay hasbeen achieved.

Safety and arming devices are intended to function to prevent the fuzingsystem from arming until an acceptable set of conditions (generally atleast two independent conditions) have been achieved.

A significant amount of effort has been expended to miniaturize militaryweapons to maximize their payload and their effectiveness and to supportunmanned missions. The physical tasking of miniaturization efforts hasbeen addressed to a great extent. However, the same cannot be saidregarding ordnance technologies that support system functionalcapabilities, for example for the case for fuzing sensors and poweringfor gravity dropped or ejected weapons.

It is important to note that simple miniaturization of subsystems alonewill not achieve the desired goal of effective fuzing for smallerweapons. This is particularly the case in regards to environmentalsensing and the use of available stimuli in support of “safe” and “arm”functionality in fuzing of small gravity dropped or ejected weapons.

A need therefore exists for the development of methods and devices thatutilize available external stimuli and relevant detectable events forthe design of innovative “safe” and “arm” (S&A) mechanisms for fuzing ofgravity dropped or ejected weapons, in particular small weapons.

SUMMARY

Accordingly, a method for generating power in a gravity droppedmunition, the method comprising: winding a cable around a drum of agenerator associated with the munition; attaching the cable from thegenerator to a portion of an aircraft; separating the munition from theaircraft to unwind the cable from the drum to release the cable from thedrum after a predetermined amount of rotation of the drum; convertingthe rotation of the drum to energy in a spring as the cable is unwoundfrom the drum; restricting movement of an intermediate member connectingthe drum to the generator while the cable is being unwound from thedrum; and ending the restricting when the cable is released from thedrum allowing the intermediate member to engage the drum with thegenerator to produce power from the generator.

The intermediate member can be a first gear connecting the drum to asecond gear at the generator.

The restricting can comprise restricting rotation of the intermediatemember in a same direction as an unwinding direction of the drum as thecable is unwound from the drum. The restricting can comprise permittingrotation of the intermediate member in a direction opposite to the samedirection as the unwinding direction of the drum as the cable is unwoundfrom the drum.

The restricting can comprise routing the cable through a portion of theintermediate member to restrict all movement of the intermediate memberas the cable is unwound from the drum.

The method can further comprise restricting a movement of the drum in adirection opposite to an unwinding direction as the cable is unwoundfrom the drum. The method can further comprise removing the restrictingof the movement of the drum in the direction opposite to an unwindingdirection after the cable is fully unwound from the drum.

Also provided is a device for generating power in a gravity droppedmunition, the device comprising: a drum; a cable wound around a drum; agenerator for producing electrical energy; a spring configured toconvert rotation of the drum to energy as the cable is unwound from thedrum; and an intermediate member selectively engaging the drum to thegenerator; wherein the intermediate member is disengaged from the drumwhen the cable is being unwound from the drum and the intermediatemember is engaged with the generator when the cable is released from thedrum to produce power from the generator.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the apparatus ofthe present invention will become better understood with regard to thefollowing description, appended claims, and accompanying drawings where:

FIG. 1 illustrates an isometric view of one embodiment of the gravitydropped or ejected weapon release event detection device with anintegrated electrical generator.

FIG. 2 illustrates the internal components of the gravity dropped orejected weapon release event detection device with an integratedelectrical generator of FIG. 1 from the device top.

FIG. 3 illustrates a cross-sectional view of the gravity dropped orejected weapon release event detection device with an integratedelectrical generator of FIG. 1 showing the internal components of thedevice.

FIG. 4 illustrates the frontal view of the cross-sectional view of FIG.3.

FIG. 5 illustrates the power spring assembly inside the two-piece drumof the gravity dropped or ejected weapon release event detection devicewith an integrated electrical generator of FIG. 1.

FIG. 6 illustrates the ratchet mechanism between the gear and thetwo-piece drum of the gravity dropped or ejected weapon release eventdetection device with an integrated electrical generator of FIG. 1.

FIG. 7 illustrates one possible mounting of the gravity dropped orejected weapon release event detection device with an integratedelectrical generator of FIG. 1 to a weapon.

FIG. 8 illustrates an isometric view of another embodiment of thegravity dropped or ejected weapon release event detection device with anintegrated electrical generator.

FIG. 9 illustrates a cross-sectional view of the gravity dropped orejected weapon release event detection device with an integratedelectrical generator of FIG. 8 showing the internal components of thedevice.

FIG. 10 illustrates the frontal view of the cross-sectional view of FIG.9.

FIG. 11 illustrates the cut-away view of the top section of the releaseevent detection and generator of FIG. 8 showing the one-way shaftlocking mechanism of the device.

FIG. 12 illustrates the top view of the release event detection andgenerator cut-away view of FIG. 11.

FIG. 13 illustrates the cross-section A-A of FIG. 10 showing the powerspring assembly inside the release event detection and generatorembodiment of FIG. 8.

FIG. 14 illustrates the cable exit points from the cable drum assemblyto the outside of the release event detection and generator embodimentof FIG. 8.

FIG. 15 illustrates a cut-away view of the top section of the releaseevent detection and generator of FIG. 8 showing the passing of the cablethrough the holes provided in the device gear and casing.

FIG. 16 illustrates a cross-sectional frontal view of an alternativeembodiment gravity dropped or ejected weapon release event detectiondevice with an integrated electrical generator showing the internalcomponents of the device.

DETAILED DESCRIPTION

FIG. 1 illustrates one embodiment of the gravity dropped or ejectedweapon release event detection device with an integrated electricalgenerator, generally referred to by reference numeral 100 andalternatively referred to hereinafter simply as a “release eventdetection and generator.” The overall dimensions of the cylindricalrelease event detection and generator 100 are 2.1 inch in diameter and0.44 inch in height and the generator of the device upon pulling thedevice cable upon weapon release is over 100 mJ. However, those skilledin the art will appreciate that other shapes and/or sizes, as well asbeing configured for other power outputs, are also possible. FIG. 1shows a casing 102 having a power output, such as a wire 104 and alanyard 106 extending therefrom. FIG. 2 shows the top view of therelease event detection and generator 100 of FIG. 1 with the devicecasing top plate shown as transparent to show the internal components ofthe device. FIG. 3 is a cross-sectional view of the release eventdetection and generator 100 of FIG. 1 showing most of the internal partsof the device. In the cross-sectional view of FIG. 3 the potentialenergy storage spring element 118 of the release event detection andgenerator 100 is shown and its assembly into the device 100 and itsoperation is described later in this disclosure.

The release event detection and generator 100 of FIG. 1 is provided witha two-piece casing 121, with a top component 110 and a bottom component111 as shown in FIG. 3, which are connected together by four screws 112.The proper positioning of the top and bottom components 110 and 111,respectively, during the assembly is ensured by the provided twolocating pins 113 as shown in FIG. 2.

The cable drum is also two-piece as indicated by a top component 114 anda bottom component 115 as can be seen in the frontal view of FIG. 4 ofthe cross-sectional view of FIG. 3. The cable drum assembly of the twocomponents 114 and 115 is indicated in FIGS. 3 and 4 and laterillustrations with the numeral 117. The two components 114 and 115 areconnected together by at least two screws (not shown), after thepotential energy storing power spring 118 has been assembled into thecable drum as can be seen in FIG. 4. As can be seen in FIG. 5, the cabledrum assembly 117 is mounted inside the two-piece casing 121 is via thebuilt-in ball bearings 119 and 120, provided between the top component110 of the two-piece casing 121 and the top component 114 of the cabledrum assembly 117 and between the bottom component 111 of the two-piececasing 121 and the bottom component 115 of the cable drum assembly 117,respectively, to minimize friction losses as the cable drum assembly 117rotates, FIG. 4.

A shaft 122 is securely mounted and centered inside the cable drumassembly 117 by the provided steps 123 during the cable drum assembly.The shaft 122 is provided with the slot 124, within which the inner end125 of the potential energy storing power spring 118 is held as shown inFIG. 5. The shaft 112 is also provided by a slot 126 on its top end atthe top component 110 of the two-piece casing 121, FIGS. 2 and 4, inwhich the end of the side 127 of a U-shaped spring element 129 ispositioned at the time of the release event detection and generator 100assembly. The side 128 of the U-shaped spring element 129 is fixedlyattached to the inside surface of the top component 110 of the two-piececasing 121, FIG. 2, in a provided groove (not shown in FIG. 2), whileits side 127 is free to rotate relative to the side 128. In theconfiguration shown in FIG. 2, the free end of the side 127 of theU-shaped spring element 129 is positioned inside the slot 126 on the topside of the shaft 122. As a result, the shaft 122 is prevented fromrotating in the counterclockwise direction as observed in the isometricview of FIG. 2. It is noted that the sides 127 and 128 of the U-shapedspring element 129 are essentially touching in normal conditions and theside 127 has to be forcibly rotated away from the fixed side 128 toinsert its end into the slot 126 of the shaft 122. As a result, once theshaft 126 is rotated in the clockwise direction as viewed in FIG. 2, theengaging free end of the side 127 exits the slot 126 on the shaft 122and is returned into essential contact with the side 128 of the U-shapedspring element 129. As a result, the shaft 122 is then free to rotate ineither clockwise or counterclockwise direction.

The outer end 144 of the potential energy storing power spring 118 isfixed to the inner side of the cable drum assembly 117 in the providedslot 147 as shown in FIG. 5.

A gear 130 is assembled onto the top component 114 of the cable drumassembly 117 as shown in FIG. 2 and is held in the viewed position bythe retaining ring 131. The gear 130 is free to rotate with respect tothe cable drum assembly 117, but is provided with a ratchet typemechanism 146 that allows counterclockwise rotation of the cable drumassembly 117 relative to the gear 130 (as held fixed relative to thetwo-piece casing 121), but prevents clockwise rotation of the cable drumassembly 117 relative to the gear 130.

The details of a possible ratchet mechanism 146 that is provided betweenthe gear 130 and the cable drum assembly 117 is shown in FIG. 6. As canbe seen in FIG. 6, the ratchet mechanism 146 consists of the pawl 149,which is fixedly attached to the bottom surface of the gear 130, and ispreferably made of a bent strip of spring steel which is attached to thegear 130 by crimping in a provided slot or when space allows at leastone screw or rivet (not shown). The pawl 149 is thereby provided withits integral spring action and living rotary joint, therebysignificantly simplifying its design and requiring a very small spacefor its assembly and operation. The top surface of the top component 114of the cable drum assembly 117 is provided with preferably equallyspaced grooves 148, with which the pawl 149 engages to provide theratcheting function that was previously described.

The gear 130 is engaged with the pinion 132, which drives the shaft 133of the electromagnetic generator 134. The shaft 133 is supported by theball bearings 136 and 136, which are mounted in the top component 110and bottom component 111, respectively, of the two-piece casing 121, asshown in FIG. 4. The output of the electromagnetic generator 134 iscarried out by the wire 104, FIGS. 1 and 2, that passes through aprovided opening on the side of the bottom component 111 of thetwo-piece casing 121.

One end of a cable 137 is securely held to the inside wall of theU-shaped groove 138 around the cable drum assembly 117, FIG. 4,preferably tightly in a radial hole or tangential groove (not shown).The cable 137 is then wound several turns (8 turns in FIG. 4) around thecable drum assembly 117 inside the U-shaped groove 138. The cable 137 isthen passed through the provided hole 139 in the gear 130, FIG. 2, andthrough the hole 140 in the top component 110 of the two-piece casing121, as shown in FIG. 3.

The release event detection and generator 100 of FIG. 1 is used inoperation as follows. As an example, the event detection and generator100 may be mounted inside the weapon 142, with the cable 106 of theevent detection and generator brought out through a provided hole (notshown) in the shell of the weapon. Once the weapon is mounted onto therack or the like of the aircraft, the end 141 of the cable 106 is firmlyattached to the aircraft, usually via a rack.

When the weapon 142 is released from the rack or ejected from theaircraft, the separation of the weapon from the aircraft due to gravityand/or ejection force will begin to pull the cable 106 out of therelease event detection and generator 100 of FIGS. 1 and 2 through theopening 143 in the weapon. As the cable 106 begins to be pulled from therelease event detection and generator 100, the cable drum assembly 117begins to rotate in the counterclockwise direction as the release eventdetection and generator 100 is viewed in FIG. 2. During this time, theend of the side 127 of a U-shaped spring element 129 is engaged with theslot 126 on the shaft 122, thereby preventing it from rotating with thecable drum assembly in the counterclockwise direction as viewed in FIG.2. As a result, the shaft 122 and thereby the inner end 125 of thepotential energy storing power spring 118 is held fixed to the two-piececasing 121 of the release event detection and generator 100, which is inturn fixedly attached to the released weapon 142. However, since theouter end 144 of the potential energy storing power spring 118 is fixedto the inside of the cable drum assembly 117, as the cable drum assembly117 is rotated in the counterclockwise direction as viewed in FIG. 2,the potential energy storing power spring 118 is wound and potentialenergy is stored in the power spring 118.

The cable drum assembly 117 is rotated in the counterclockwise directionas the release event detection and generator 100 is viewed in FIG. 2 andincreasing amounts of potential energy keeps on being stored in thepotential energy storing power spring 118 by its increased winding untilthe end of the cable 106 that is securely held to the inside wall of theU-shaped groove 138 around the cable drum assembly 117, FIG. 4, isreached and the said end is pulled through the hole 139 in the gear 130,FIG. 2, and through the hole 140 in the top component 110 of thetwo-piece casing 121, as shown in FIG. 3.

It is appreciated that while the cable drum assembly 117 is beingrotated by the pulling of the cable 106 in the counterclockwisedirection as the release event detection and generator 100 is viewed inFIG. 2, the ratchet type mechanism 146 allows counterclockwise rotationof the cable drum assembly 117 relative to the gear 130 (as held fixedrelative to the two-piece casing 121).

Then as the end of the cable 106 exits the hole 139 in the gear 130,FIG. 2, the gear becomes free to rotate.

At this point, the wound potential energy storing power spring 118begins to unwind and transfer its stored potential energy to the cabledrum assembly 117 by rotating it in the clockwise direction as therelease event detection and generator 100 is viewed in FIG. 2. At thistime, the ratchet type mechanism 146 which only allows counterclockwiserotation of the cable drum assembly 117 relative to the gear 130, isalso forced to rotate with the cable drum assembly 117 by the ratchettype mechanism 146. The gear 130 will in turn begin to rotate the pinion132 of the electromagnetic generator 134 and cause it to begin togenerate electrical energy.

At this time, the voltage (current) generated by the electromagneticgenerator 134 indicates the exit of the end of the cable 106 from therelease event detection and generator 100, thereby indicating the eventof weapon release from the aircraft. The release event can thereby bedetected by the weapon fuzing electronics and all other electrical andelectronic devices onboard the weapon.

The wound potential energy storing power spring 118 will keep unwindingand transferring its stored potential energy to the clockwise rotatingcable drum assembly 117 and the gear 130 until it is fully unwound. Atthis time the cable drum assembly 117 will begin to force the potentialenergy storing power spring 118 to keep rotating in the clockwisedirection, as a result of which the inner end 125 of the power spring118 begins to rotate the shaft 122 in the clockwise direction as therelease event detection and generator 100 is viewed in FIG. 2. Theclockwise rotation of the shaft 122 causes the end of the side 127 ofthe U-shaped spring element 129 to disengage the slot 126 on the shaft122, FIG. 2, thereby causing the assembly of the shaft 122, thepotential energy storing power spring 118, the cable drum assembly 117,and the gear 130 to keep on rotating together in the clockwise directionas the release event detection and generator 100 is viewed in FIG. 2.The kinetic energy stored in the latter clockwise rotating assemblage istransferred to the electromagnetic generator 134 by the gear 130 via thepinion 132 to generate electrical energy.

FIG. 8 illustrates another embodiment 150 of the gravity dropped orejected weapon release event detection device with an integratedelectrical generator of the present invention, hereinafter also referredto simply as a “release event detection and generator.” The overalldimensions of the cylindrical release event detection and generator 150are 1.5 inch in diameter and 1.5 inch in height and the generator of thedevice upon pulling the device cable upon weapon release is over 200 mJ.However, those skilled in the art will appreciate that other shapesand/or sizes, as well as being configured for other power outputs, arealso possible.

As can be seen in FIG. 8, the release event detection and generator 150is constructed with a two-piece casing, indicated by numerals 151 and152 in FIG. 8. The two pieces 151 and 152 of the casing are fixedlyattached by preferably more than one screw 155. The two-piece casingassembly is indicated by the numeral 164, FIG. 10.

FIG. 8 shows the release event detection and generator 150 having apower output, such as a wire 153 and a lanyard 154 that is exiting fromthe hole 156 provided in the top piece 152 of the device casing.Attached to the top piece 152 of the casing 164 of the release eventdetection and generator 150 is the “electromagnetic generator assembly”157, which is constructed as a separate module, and is attached to thetop piece 152 of the casing by screws 158.

FIG. 9 is a cross-sectional view of the release event detection andgenerator 150 of FIG. 8 showing most of the internal parts of thedevice. In the cross-sectional view of FIG. 9 the potential energystorage spring element 159 of the release event detection and generator150 is clearly shown for and its assembly and operation is describedlater in this disclosure.

The cable drum is also two-piece as indicated by a top component 160 anda bottom component 161 as can be seen in the cross-sectional view ofFIG. 9 and its frontal view of FIG. 10. The cable drum assembly with thetwo components 160 and 161 is indicated in FIG. 9 and in laterillustrations by the numeral 163. The two components 160 and 161 areconnected together by at least two screws 162, after the potentialenergy storing power spring 159 has been assembled into the cable drum163.

As can be seen in FIG. 10, the cable drum assembly 163 is mounted insidethe two-piece casing 164 on the shaft 165 by the ball bearing 166 on thetop as viewed in FIG. 10, and rides directly on the shaft 165 on thebottom side, where it is held in position by the retaining ring 167 thatis mounted in a groove on the shaft. In FIG. 10 the base surface of thetwo-piece casing 164 is provided with a recess 168 to accommodate theretaining ring 167 for the purpose of minimizing the occupied space.

The shaft 165 is centrally mounted inside the two-piece casing 164 onthe top (as viewed in FIG. 10) by the ball bearing 169, which is mountedin the top piece 152 of the casing 164, and on the bottom by the ballbearing 170, which is mounted in the bottom piece 151 of the casing 164.It noted that as can be seen in FIG. 10, the ball bearing 170 is mountedinside the shaft 165 by its outer race in a provided pocket and that theinner race of the ball bearing 170 is mounted in a provided cylindricalappendage 171 inside the bottom piece 151 of the casing 164. This methodof assembly provides for a compact assembly for the release eventdetection and generator 150.

FIG. 13 shows the cross-section A-A of FIG. 10. The shaft 165 isprovided with the slot 172, FIGS. 10 and 13, within which the inner end173 of the potential energy storing power spring 159 is held as shown inFIG. 13. The outer end 197 of the potential energy storing power spring159 is fixed to the inner side of the bottom component 161 of the cabledrum assembly 163 over the provided end 198 of the slot 199, as shown inthe cross-section view of FIG. 13.

The shaft 165 is also provided with a slot 174 on its top end as isshown in FIG. 11 and its top view of FIG. 12 (in which the top portionof the shaft, FIG. 11, is cut out to clearly show the slot 174), inwhich one end 175 of the U-shaped spring element 176 is positioned atthe time of the release event detection and generator 150 assembly. Theother side 177 of the U-shaped spring element 176 is fixedly attached tothe inside surface of the surface 179 provided on the top piece 152 ofthe casing 164 by the screws 178 as is shown in FIG. 11. As a result,the shaft 165 is prevented from rotating in the counterclockwisedirection relative to the casing 164 of the release event detection andgenerator 150 as observed in the isometric view of FIG. 11 and the topview of FIG. 12. It is noted that the U-shaped spring element 176 isnormally flat and that the end 175 is deflected elastically away fromthe surface 179 to be inserted into the slot 174 of the shaft 165. As aresult, once the shaft 165 is rotated in the clockwise direction asviewed in FIGS. 11 and 12, the engaging free end of the side 175 exitsthe slot 174 on the shaft 165 and is returned into essential contactwith the side 179 of the top piece 152 of the casing 164. As a result,the shaft 165 is then free to rotate in either clockwise orcounterclockwise direction.

One end of a cable 181, FIGS. 9 and 10, is securely held to the insidewall of the U-shaped groove 182 provided around the top component 160 ofthe cable drum assembly 163, FIG. 10, preferably tightly in a radialhole or tangential groove (not shown). The cable 181 is then woundseveral turns (8 turns in FIG. 10) around the cable drum assembly 163inside the U-shaped groove 182. The cable 181 is then passed through theprovided hole 183 in the gear 180 and through the hole 156 in the topcomponent 152 of the two-piece casing 164, as shown in FIG. 14.

A gear 180 is assembled onto the neck 184 of the top component 160 ofthe cable drum assembly 163, FIG. 10, and is held in the viewed positionby the retaining ring 184 as shown in FIGS. 10 and 11. The gear 180 isfree to rotate with respect to the cable drum assembly 163, but isprovided with a ratchet type mechanism consisting of at least one link186 which is integral to the gear 180 and attached to it with a livingrotary joint 189 as shown in FIG. 15. The link 186 together with itsdownward extended tip 187, FIG. 15, constitute the pawl of the ratchetmechanism between the gear 180 and the top component 160 of the cabledrum assembly 163. The top surface of the top component 160 of the cabledrum assembly 163 is provided with preferably equally spaced radiallydirected grooves 188 (preferably at least every 15-20 degrees), for thetip 187 of the pawl to engage. As can be observed in FIG. 15, theprovided ratchet mechanism between the gear 180 and the top component160 of the cable drum assembly 163 allows counterclockwise rotation ofthe top component 160 and thereby the cable drum assembly 163, FIG. 10,relative to the gear 180, but prevents clockwise rotation of the cabledrum assembly 163 relative to the gear 180. It is noted that in theassembled release event detection and generator 150 and before itsactivation as described later in this disclosure, the cable 154 preventsrotation of the gear 180 relative to the two-piece casing 164 by passingthrough the provided hole 183 in the gear 180 and the hole 156 in thetop component 152 of the two-piece casing 164, as shown in FIG. 14.

The gear 180 is engaged with the pinion 190, which drives the shaft 191of the electromagnetic generator 192, FIG. 10. The shaft 191 issupported by the ball bearings 193 and 194, which are mounted in the“electromagnetic generator assembly” 157, FIGS. 8-10, of the topcomponent 152 of the two-piece casing 164. The output of theelectromagnetic generator 192 is carried out by the wire 153, FIGS. 8and 10, that passes through a provided opening 195 on the side of the“electromagnetic generator assembly” 157, FIG. 9.

The release event detection and generator 150 of FIG. 8 is used inoperation similar to the embodiment 100 of FIG. 1. As an example, theevent detection and generator 150 may also be mounted inside the weapon142 of FIG. 7, with the cable 154 (106 in FIG. 7) of the event detectionand generator 150, FIG. 8, brought out through a provided hole (notshown) in the shell of the weapon 142. Once the weapon is mounted ontothe rack or the like of the aircraft, the end 186 shown in FIG. 8 (141in FIG. 7) of the cable 154 is firmly attached to the aircraft, usuallyvia a rack.

When the weapon 142 is released from the rack or ejected from theaircraft, the separation of the weapon from the aircraft due to gravityand/or ejection force will begin to pull the cable 154 out of therelease event detection and generator 150 of FIG. 8 through the opening143 in the weapon. As the cable 154 begins to be pulled from the releaseevent detection and generator 150, the cable drum assembly 163, FIG. 10,begins to rotate in the counterclockwise direction as the release eventdetection and generator 150 is viewed in FIGS. 8 and 9. During thistime, the end of the side 175 of the U-shaped spring element 176 isengaged with the slot 174 on the shaft 165, FIG. 12, thereby preventingit from rotating with the cable drum assembly 163 in thecounterclockwise direction as viewed in FIGS. 8 and 9. As a result, theshaft 165 and thereby the inner end 173 of the potential energy storingpower spring 159 is held fixed to the two-piece casing 164 of therelease event detection and generator 150, which is in turn fixedlyattached to the released weapon 142. However, since the outer end 197 ofthe potential energy storing power spring 159 is fixed to the inside ofthe cable drum assembly 163, as the cable drum assembly 163 is rotatedin the counterclockwise direction as viewed in FIGS. 8 and 9, thepotential energy storing power spring 159 is wound and potential energyis stored in the said power spring.

The cable drum assembly 163 is rotated in the counterclockwise directionas the release event detection and generator 150 is viewed in FIG. 9 andincreasing amounts of potential energy is stored in the potential energystoring power spring 159 by its increased winding until the end of thecable 154 that is securely held to the inside wall of the U-shapedgroove 182 around the cable drum assembly 163, FIG. 10, is reached andthe said end is pulled through the hole 183 in the gear 180 and the hole156 in the top component 152 of the two-piece casing 164, as shown inFIG. 14. At this time the gear 180 becomes free to rotate relative tothe two-piece casing 164 of the release event detection and generator150.

It is appreciated that while the cable drum assembly 163 is beingrotated by the pulling of the cable 154 in the counterclockwisedirection as the release event detection and generator 150 is viewed inFIGS. 8 and 9, the ratchet type mechanism shown in FIG. 15 allowscounterclockwise rotation of the cable drum assembly 163 relative to thegear 180 (as being held fixed relative to the two-piece casing 164).

At this point, the wound potential energy storing power spring 159begins to unwind and transfer its stored potential energy to the cabledrum assembly 163 by rotating it in the clockwise direction as therelease event detection and generator 150 is viewed in FIGS. 8 and 9. Atthis time, the ratchet type mechanism shown in FIG. 15 which only allowscounterclockwise rotation of the cable drum assembly 163 relative to thegear 180, is also forced to rotate with the cable drum assembly 163 bythe said ratchet type mechanism. The gear 150 will in turn begin torotate the pinion 190 of the electromagnetic generator 192 and cause itto begin to generate electrical energy.

At this time, the voltage (current) generated by the electromagneticgenerator 192 indicates the exit of the end of the cable 154 from therelease event detection and generator 150, thereby indicating the eventof weapon release from the aircraft. The release event can thereby bedetected by the weapon fuzing electronics and all other electrical andelectronic devices onboard the weapon.

The wound potential energy storing power spring 159 will keep unwindingand transferring its stored potential energy to the clockwise rotatingcable drum assembly 163 and the gear 180 until it is fully unwound. Atthis time the cable drum assembly 163 will begin to force the potentialenergy storing power spring 159 to keep rotating in the clockwisedirection, as a result of which the inner end 173 of the power spring159 begins to rotate the shaft 165 in the clockwise direction as therelease event detection and generator 150 is viewed in FIGS. 8 and 9.The clockwise rotation of the shaft 165 causes the end of the side 175of the U-shaped spring element 176 to disengage the slot 174 on theshaft 165, FIG. 11, thereby causing the assembly of the shaft 165, thepotential energy storing power spring 159, the cable drum assembly 163,and the gear 180 to keep on rotating together in the clockwise directionas the release event detection and generator 150 is viewed in FIGS. 8and 9. The kinetic energy stored in the latter clockwise rotatingassemblage is thereby transferred to the electromagnetic generator 192by the gear 180 via the pinion 190 to generate electrical energy.

As can be seen in the FIGS. 3 and 4 of the embodiment 100, the cabledrum is constructed in two-pieces as indicated by a top component 114and a bottom component 115. The cable drum assembly of the twocomponents 114 and 115 is indicated in FIGS. 3 and 4 and together asnumeral 117. The two components 114 and 115 are connected together by atleast two screws (not shown), after the potential energy storing powerspring 118 has been assembled into the cable drum as can be seen in FIG.4. As can be seen in FIG. 4, the cable drum assembly 117 is mountedinside the two-piece casing 121 via the built-in ball bearings 119 and120, provided between the top component 110 of the two-piece casing 121and the top component 114 of the cable drum assembly 117 and between thebottom component 111 of the two-piece casing 121 and the bottomcomponent 115 of the cable drum assembly 117, respectively, to minimizefriction losses as the cable drum assembly 117 rotates, FIG. 4.

The built-in ball bearings 119 and 120, FIGS. 3 and 4, however, haverelatively large diameters, and their races are machined in the topcomponent 110 of the two-piece casing 121 and the top component 114 ofthe cable drum assembly 117 and between the bottom component 111 of thetwo-piece casing 121 and the bottom component 115 of the cable drumassembly 117, respectively. Such races, having been machined in separatehalves, do not also generally have the precision, smooth surface andsurface hardness that are provided in regular ball bearings. As aresult, the rolling friction coefficient of the machined built-in ballbearings 119 and 120, FIGS. 3 and 4, may be significantly higher thanmass-produced precision ball bearings. In addition, even if the built-inball bearings 119 and 120 could be made with coefficients of friction ofthe order of the mass-produced precision ball bearings, their largediameters would generate relatively large friction moments that wouldoppose the rotation of the cable drum assembly 117. As a result, aconsiderable amount of the potential energy stored in the power spring118 at the time of its release is consumed by the losses due to thefriction moments of the built-in ball bearings 119 and 120, FIGS. 3 and4.

An alternative design of the event detection and electrical generatorembodiment 100 of FIGS. 1-6 is provided, which would avoid the use ofthe built-in ball bearings 119 and 120 in order to minimize the amountof mechanical energy that is lost due to the bearing friction. Such adesign is of particular interest when a prescribed amount of energy isto be generated by the event detection and electrical generator and thedevice is desired to be as small as possible. The alternative design ofthe event detection and electrical generator embodiment 100 of FIGS.1-6, which minimizes the friction losses by replacing the built-in ballbearings 119 and 120 by significantly smaller and mass-producedprecision ball bearings is shown in FIG. 16 and is indicated by thenumeral 200.

The frontal cross-sectional view of the alternative embodiment 200 ofthe event detection and electrical generator embodiment 100 of FIGS. 1-6is shown in FIG. 16. All components of the event detection andelectrical generator embodiment 200 are similar to those of theembodiment 100 of FIGS. 1-6, except for the following modifications.

In the embodiment 100 of FIGS. 1-6 and as can be seen in FIG. 4, thecable drum assembly 117 is mounted inside the two-piece casing 121 viathe built-in ball bearings 119 and 120, provided between the topcomponent 110 of the two-piece casing 121 and the top component 114 ofthe cable drum assembly 117 and between the bottom component 111 of thetwo-piece casing 121 and the bottom component 115 of the cable drumassembly 117, respectively. However, in the alternative embodiment 200of FIG. 16, the built-in ball bearings 119 and 120 are eliminated, butthe cable drum assembly 117 is still similarly mounted over the shaft201 (similar to the shaft 122 in the embodiment 100, FIG. 4). However,in the alternative embodiment 200 of FIG. 16, the shaft 201 itself isprovided with an internal shaft 202, which is mounted inside the shaft210 via ball bearings 203 and 204, which are in turn mounted in the topcomponent 110 and the bottom component 111 of the two-piece casing 121event detection and electrical energy generator embodiment 200.

As a result, once released, the cable drum assembly 117 together withthe shaft 201 can now freely rotate about the internal shaft 202, viathe ball bearings 203 and 204. As a result, by replacing the largediameter and built-in ball bearings 119 and 120 which are generallylower in precision (due to races that are not hardened and precisionfinished) by significantly smaller diameter ball (or other similar)precision bearings 203 and 204, the friction losses due to thesebearings are significantly reduced.

The alternative event detection and electrical energy generatorembodiment 200, FIG. 16, otherwise operates as was described for theevent detection and electrical energy generator embodiment 100 of FIG.1-6.

It will be appreciated by those having ordinary skill in the art thatsince as was described for the event detection and electrical energygenerator embodiment 100 of FIG. 1-6, during the weapon release, FIG. 7,the cable 137, FIG. 4, is pulled essentially in a direction tangent tothe cable drum assembly 117 inside the U-shaped groove 138. As a result,the force exerted by the cable 137 generates minimal bending moment inthe direction perpendicular to the shaft 122 in the embodiment 100, FIG.4, as well as to the shafts 201 and 202 in the alternative embodiment200 of FIG. 16. As a result, the built-in ball bearings 119 and 120 inthe embodiment 100 of FIGS. 1-6 and the ball bearings 203 and 204 of theembodiment 200 of FIG. 16 are subjected to negligible axial loads andrelatively low lateral load (only due to the cable pulling force). As aresult, the replacement of the large diameter built-in ball bearings 119and 120 in the embodiment 100 of FIGS. 1-6 with the small diameter ballbearings 203 and 204 of the embodiment 200 of FIG. 16 has negligibleeffect on the integrity and operation of the event detection andelectrical energy generator. However, it does significantly reducefriction losses, which may amount to as high as 30-50 percent of theavailable mechanical energy of the power spring for conversion toelectrical energy.

While there has been shown and described what is considered to bepreferred embodiments of the invention, it will, of course, beunderstood that various modifications and changes in form or detailcould readily be made without departing from the spirit of theinvention. It is therefore intended that the invention be not limited tothe exact forms described and illustrated, but should be constructed tocover all modifications that may fall within the scope of the appendedclaims.

What is claimed is:
 1. A method for generating power in a gravitydropped munition, the method comprising: winding a cable around a drumof a generator associated with the munition; attaching the cable fromthe generator to a portion of an aircraft; separating the munition fromthe aircraft to unwind the cable from the drum to release the cable fromthe drum after a predetermined amount of rotation of the drum;converting the rotation of the drum to energy in a spring as the cableis unwound from the drum; restricting movement of an intermediate memberconnecting the drum to the generator while the cable is being unwoundfrom the drum; and ending the restricting when the cable is releasedfrom the drum allowing the intermediate member to engage the drum withthe generator to produce power from the generator.
 2. The method ofclaim 1, wherein the intermediate member is a first gear connecting thedrum to a second gear at the generator.
 3. The method of claim 1,wherein the restricting comprises restricting rotation of theintermediate member in a same direction as an unwinding direction of thedrum as the cable is unwound from the drum.
 4. The method of claim 3,wherein the restricting comprises permitting rotation of theintermediate member in a direction opposite to the same direction as theunwinding direction of the drum as the cable is unwound from the drum.5. The method of claim 1, wherein the restricting comprises routing thecable through a portion of the intermediate member to restrict allmovement of the intermediate member as the cable is unwound from thedrum.
 6. The method of claim 1, further comprising restricting amovement of the drum in a direction opposite to an unwinding directionas the cable is unwound from the drum.
 7. The method of claim 6, furthercomprising removing the restricting of the movement of the drum in thedirection opposite to an unwinding direction after the cable is fullyunwound from the drum.
 8. A device for generating power in a gravitydropped munition, the device comprising: a drum; a cable wound around adrum; a generator for producing electrical energy; a spring configuredto convert rotation of the drum to energy as the cable is unwound fromthe drum; and an intermediate member selectively engaging the drum tothe generator; wherein the intermediate member is disengaged from thedrum when the cable is being unwound from the drum and the intermediatemember is engaged with the generator when the cable is released from thedrum to produce power from the generator.